This invention relates generally to a gear configuration having a fixed center distance between parallel gears to eliminate backlash, and more particularly, to elimination of the lack of movement in a driven gear in the event of a change in rotational direction of the driver gear.
In the prior art, gear set assemblies involved in transmitting angular movement from one shaft to another generally accommodate a relatively large tolerance to lash intrinsic with fabrication, and assembly of such gear set assemblies. In any gear set, backlash, or clearance between a tooth of one of the gears as it fills the space between two teeth of another gear, is necessary in the meshed engagement of the teeth of a gear in order to permit relative motion between two gears. In a gear system with no backlash, the meshing of the teeth between gears will be so tight that, absence any deflection of the teeth, the gears will bind and cause the system to jam.
Various attempts to de-lash a gear system are well known in the prior art. The de-lashing of non-fixed parallel gear sets by adjusting the center distance between the gears is well understood and is usually accomplished using a spring or screw-type adjustment. These methods are generally effective through a very narrow range of manufacturing variability. More specifically, some attempts at so-called xe2x80x9cactive de-lashingxe2x80x9d exist using the same shaped parallel gears and a spring to make the apparent tooth width bigger that accomplishes both lash control and fixed center distance. However, the de-lash is not suitable when using a spring having a low spring rate and rotation of the final gear assembly is difficult when using a spring having a high spring rate. A hand-wheel position sensor is one implementation requiring a pair of gears having a fixed center distance while zero backlash is recommended.
Thus, there remains a need to control backlash for rotating gears having a fixed center distance from each other while meshingly engaged in substantially the same plane.
A mechanism for de-lashing a gear assembly includes a first gear rotatable about a first axis having a first center rotatably fixed to the first axis and a first conical teeth portion. The gear assembly includes a second gear rotatable about a second axis having a second center rotatably fixed to said second axis and a second conical teeth portion configured to meshingly engage first conical teeth portion when the first and second gears are aligned substantially coplanarly. A biasing means operably biases the second conical teeth portion of the second gear against the first conical teeth portion of the first gear to reduce any lash therebetween. The biasing means is configured to bias the second gear in an axial direction while maintaining a fixed center distance between the first and second axes. The first gear is rotatably fixed about the fixed first axis such that the first gear is prevented from translation along the fixed first axis.
In one embodiment, the de-lashing gear assembly is employed with a hand-wheel position sensor configured to sense the rotational position of a motor vehicle hand-wheel. The hand-wheel position sensor includes a housing; a PCB disposed within said housing; a sensor operably connected to circuitry on said PCB; and a gear assembly operably connected to the sensor having a mechanism for de-lashing the gear assembly. The gear assembly includes a first gear rotatable about a first axis having a first center rotatably fixed to the first axis and a first conical teeth portion. The gear assembly includes a second gear rotatable about a second axis having a second center rotatably fixed to said second axis and a second conical teeth portion configured to meshingly engage first conical teeth portion when the first and second gears are aligned substantially coplanarly. A biasing means operably biases the second conical teeth portion of the second gear against the first conical teeth portion of the first gear to reduce any lash therebetween. The biasing means is configured to bias the second gear in an axial direction while maintaining a fixed center distance between the first and second axes. The first gear is rotatably fixed about the fixed first axis such that the first gear is prevented from translation along the fixed first axis.
The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims.